The development of the fire sprinkler system many years ago has made a major impact upon the minimization of damage to the structure and contents of buildings which are so protected. The classic fire sprinkler system includes a distribution system of piping secured to a ceiling with downward extending stub lines which support an individual sprinkler head. The sprinkler heads are usually fire or temperature responsive to melt a fusible link and release a shower of water to the protected space below. Typically these sprinkler heads are located a fixed distance apart to provide area coverage without fail.
In the case of installations in warehouses and factories, the sprinkler heads and piping are fully exposed since aesthetics are not usually a consideration. However, in the cases of retail establishments, offices and residential locations, it is desired that the fire sprinklers blend in with the ceiling as much as possible while maintaining its full operating capacity.
It has been proposed that adjustable mounts be provided for sprinkler heads to make them virtually flush and adjustable to be integrated in a suspended or false ceiling. An example of such a system is disclosed in U.S. Pat. No. 4,785,887 issued Nov. 22, 1988 to Peter Miller of Arlington, Va. and assigned on its face to Lifesaving Systems, Inc.
It has also been proposed that such a fire prevention system be integrated into the grid system of a suspended or false ceiling with sprinkler heads located at grid intersections. Such a system adds to the cost of the grid system and makes them integrated. Any change in the ceiling grid system will affect the sprinkler system. Such a system is disclosed in U.S. Pat. No. 4,791,993 issued on Dec. 20, 1988 to Jeremiah M. Curran of Yardley, Pa.
Where it is desired to mount a fire sprinkler system in a suspended ceiling employing, for example, a 2 foot by 2 foot grid system, it is desirable to have the sprinkler heads located at the center of a grid opening and therefore be symmetrically placed in the room. With common 10 foot spacing of sprinkler heads, this is possible, provided the distribution piping which is mounted on the structural ceiling is properly located with joints for stub or drop lines located directly at the center of every fifth grid.
In the past this has been accomplished by installing the ceiling grid first and then the pipefitter locating the fire sprinkler distribution system above the grid. One difficult task has been to locate the stub line at the precise center of a grid opening. Sometimes this is done by eye by the pipefitter or in some cases he has resorted to making a crude T guide from three straight arms, each of 1 foot length to provide a reference center point and then use a plumb bob, moving the line at the structural ceiling until the bob is over the intersection of the T and then mark the structural ceiling as a joint location. To avoid "drifting" of the distribution line with respect to the ceiling grid system, the same measurement must be taken at each grid opening which will have a sprinkler head. After the job is finished the T tool is usually discarded and the plumb bob returned to the pipefitter's tool box for the next job.
A jig for assisting the location of a sprinkler head and marking the ceiling tiles for cutting is disclosed in U.S. Pat. No. 4,928,773 issued on May 29, 1990 to Jerry H. White of San Juan Capistrano, Calif. Another system for adjusting fire sprinklers vertically in suspended ceilings is disclosed in U.S. Pat. No. 4,834,186 to E. A. Ballard of Scottsdale, Ariz.
Other general purpose jigs and templates for piping and other applications are disclosed in the following U.S. Patents:
______________________________________ 152,487 G. F. Hawley June 30, 1874 375,795 J. Beyerle Jan. 3, 1888 2,431,100 J. A. Woods Nov. 18, 1947 3,407,509 J. S. Martinez Oct. 29, 1968 ______________________________________